I've had cowl hoods on several trucks in the past and I just chunked the underhood liner and painted the underside of the hood to match.
2014 Ram 1500 Express 'Black Edition' SCSB 2wd - 5.7 Hemi
2013 Sierra 1500 ECSB. SOLD
2012 Silverado 1500 ECSB 2wd Z71 - Black 5.3L - SOLD
2007 Silverado RCSB NNBS--Greystone Metallic 4.8L-3.73 - SOLD